There are a number of chronic diseases with poorly understood etiologies that contribute substantially to the morbidity of human populations and result in significant expenditures of public health dollars. Environmental agents may produce some of this disease, and identification of associations between exposures and certain diseases would presumably lead to the prevention of morbidity. Other than cancer, few chronic diseases have received much attention in studies of environmental hazards, yet other diseases might be the more common results of exposure to such hazards. The Epidemiology Branch is developing a program in environmental epidemiology that will address the role of environmental factors in the etiology of some less well studied chronic diseases. Studies of risk factors for cancer are also conducted when cancer is the most likely outcome of exposure or when methods for the study of cancer risk are more readily available. The program is also concerned with the development of methods for assessing environmental exposures in the context of epidemiologic studies and examining disease risk in relation to some of these measures of exposure. A multi-center case-control study of risk factors for chronic renal failure is currently being conducted. Related studies involve the development of a renal disease classification scheme for use in etiologic studies and the identification of risk factors for particular renal disease subtypes. The feasibility of other studies that relate to risk factors for chronic renal failure is also being explored. A study of the relationship of childhood and/or adulthood passive expsure to cigarette smoke and cancer risk has been completed and related proposals are being developed. Studies of the etiology of Reye's Syndrome and the specificity of the liver pathology seen in Reye's have also been completed.